"qemu-system-x86_64 -cdrom OS.iso" says "No bootable device"

When I start the OS with "qemu-system-x86_64 boot.bin" it is working perfectly fine but when I try to start it with "qemu-system-x86_64 -cdrom OS.iso" it say "No bootable device". The same when I am trying to start it with my computer from a flash drive.

boot.asm:

bits 16
org 0x7c00

start:
    call x16_clearscreen
    mov si, msg
    call x16_printstring
    call x16_getkey
    call x16_reboot
    hlt

jmp $
msg db "Press any key to restart...", 0
%include"video.asm"
%include"keyboard.asm"
%include"power.asm"
times 510-($-$$) db 0
dw 0xaa55

video.asm:

bits 16

x16_setvideomode:
    int 0x10
    ret
x16_setbackcolor:
    mov ah, 0x0b
    mov bh, 0x00
    int 0x10
    ret
x16_printchar:
    mov ah, 0x0e
    int 0x10
    ret
x16_printstring:
    .loop:
        lodsb
        cmp al, 0
        je .end
        call x16_printchar
        jmp .loop
    .end:
        ret
x16_clearscreen:
    mov ah, 0x00
    mov al, 0x02
    int 0x10
    ret

keyboard.asm:

bits 16

x16_getkey:
    mov ah, 0x00
    int 0x16
    ret

power.asm:

bits 16

x16_reboot:
    int 0x19